The RAM: Similar speeds, different levels of complexity

Finally, there's the memory, another area where the systems are pretty different from one another. Both include one big 8GB pool of system RAM that is shared between the CPU and GPU. The PS4 uses fast 5500MHz GDDR5 RAM of the type you might find on a modern graphics card, while the Xbox One uses slower 2133MHz DDR3 RAM like what you might find in a standard-issue PC. Both consoles use a 256-bit memory bus, giving the PS4 a theoretical memory bandwidth of roughly 176GB per second, while the Xbox One gets by with bandwidth of around 68.26GB per second because of its slower clock speed.

It looks like, as with the GPU, the Xbox One will fall behind here, but things aren't actually so straightforward. Microsoft has also included 32MB of high-speed ESRAM integrated directly into to processor die. 32MB doesn't sound like much compared to the 8GB pool of system RAM, but it makes up for its small size by being much, much faster. Things sent to the ESRAM don't have to travel out to main memory and back, which both increases bandwidth and reduces latency.

The maximum theoretical bandwidth for the ESRAM is a whopping 218GB per second, though that takes the form of a maximum 109GB per second traveling in either direction simultaneously. Once you take the hardware limitations of ESRAM into account, the actual theoretical bandwidth ends up being about 204GB per second or 102GB per second in either direction.

We again turn to the interview with Goossen and Baker to get more insight into the Xbox One's architecture—after accounting for the differences between real-world bandwidth and theoretical bandwidth, Baker says the DDR3 system RAM and the ESRAM can together give developers about 200GB per second of memory bandwidth to work with. In theory, the ESRAM will mitigate the need for the faster (but more expensive and more power-hungry) GDDR5 that Sony has opted to use.

That said, the Xbox One's memory configuration is less straightforward than Sony's. Developers targeting the PS4 don't have to worry about whether they want to use ESRAM or the main system RAM—they can just send everything to the big, fast pool of system memory and be done with it. The Xbox 360 used a similar eDRAM chip to increase memory bandwidth, so developers may already be used to working with this kind of a hardware setup. Still, this is another area where a resource- and time-strapped cross-platform developer might opt to simply lower the resolution or texture quality for the Xbox One version rather than fine-tune things specifically for Microsoft's memory configuration.

The real-world impact

Enlarge/ There are differences between the way the Xbox One renders something and the way the PS4 renders it, but the gap is much narrower than in previous generations.

The first wave of next-generation games is just starting to trickle out, giving us an early look at how the hardware differences between the two consoles will affect actual games. Stories from last week about Battlefield 4's resolution on both consoles are just a preview of what will start happening as gamers get the consoles in their hands and begin nitpicking.

The short version of that story is that the newest Battlefield is running at 1280×720 on the Xbox One but 1600×900 resolution on the PS4. Both versions are running at 60 frames per second and look mostly similar from a normal viewing distance of eight-to-10 feet, but at least early on it may be the case that the PlayStation 4's more straightforward memory configuration and more powerful GPU will make its games look and run a bit better. This may change as developers become more comfortable with the Xbox One's particular hardware foibles, but it will ultimately be up to them to decide what resolutions their games look best at.

"We've chosen to let title developers make the trade-off of resolution versus per-pixel quality in whatever way is most appropriate to their game content," said Goossen of the Xbox One. "We built Xbox One with a higher quality scaler than on Xbox 360, and added an additional display plane, to provide more freedom to developers in this area."

In analyzing the Battlefield resolution situation, Ars Gaming Editor Kyle Orland noted that, aside from the resolution, the scenes rendered by both consoles appeared to be identical in every way from smoke effects to textures to colors and shadows. There were differences, but they weren't very noticeable unless you happened to be sitting very near to your monitor and looking for them.

In any case, we certainly aren't looking at the kind of difference in graphical quality you see in some cross-platform games from earlier in the PS3 and Xbox 360 generation, where graphical details could differ significantly between platforms. As we've mentioned, these two consoles are largely capable of rendering the exact same scene in the exact same way. Even though the Xbox One has a slightly faster CPU, the PS4 has a larger GPU. And both consoles take different approaches to delivering developers similar amounts of memory and memory bandwidth.

One thing is clear: the era of the console wars that focused entirely on raw specifications is already on the wane following the PS3 and Xbox 360 generation. You have to dig pretty deep and have strong moral objections to resolution scaling to find significant arguments about console specs in this day and age (unless you're arguing about the Wii U, of course).

Microsoft and Sony will bend over backwards to tell you how different one console (their console) is from the competition, but in the end the boxes are very, very similar, even if they're not identical. If early games are any indication, the PS4's beefier GPU will give it the performance edge in the long term, but this console war is one that will be fought primarily with software and services, not with silicon.